This invention generally relates to flexible zippers for use in reclosable pouches, bags or other packages of the type in which perishable material, such as foodstuff, may be stored.
Reclosable fastener assemblies are useful for sealing thermoplastic pouches or bags. Such fastener assemblies often include a plastic zipper and a slider. Typically, the plastic zippers include a pair of interlockable fastener elements, or profiles, that form a closure. As the slider moves across the profiles, the profiles are opened or closed. The profiles in plastic zippers can take on various configurations, e.g. interlocking rib and groove elements having so-called male and female profiles, interlocking alternating hook-shaped closure elements, etc.
Conventional slider-operated zipper assemblies typically comprise a plastic zipper having two interlocking profiles and a slider for opening and closing the zipper. In one type of slider-operated zipper assembly, the slider straddles the zipper and has a separating finger at one end that is inserted between the profiles to force them apart as the slider is moved along the zipper in an opening direction. The other end of the slider is sufficiently narrow to force the profiles into engagement and close the zipper when the slider is moved along the zipper in a closing direction.
Other types of slider-operated zipper assemblies avoid the use of a separating finger. For example, U.S. Pat. No. 6,047,450 discloses a zipper comprising a pair of mutually interlockable profiled structures in which portions of the two profiled structures form a fulcrum about which the profiled structures may be pivoted out of engagement when lower edges of the bases are forced towards each other by the slider.
In the case of sliders having a separating finger or post for separating the zipper profiles, it is usually necessary to have the finger or post extend into the product side of the package. Since the zipper halves are relatively rigid, they do not conform to the shape of the post and a gap is left between the post and the point where the zipper halves are fully mated. This gap creates a potential for liquid and gas leakage from or into the package. From this standpoint, sliders without separating fingers or posts are an improvement.
Under circumstances that produce high forces tending to separate the profiles of a closed zipper, it is known that some zippers are more susceptible than others to being accidentally opened. This is especially true for large bags. For example, high separating forces can be generated during handling of a reclosed bag, the magnitude of the force being sufficient to cause the bag to open accidentally. There is a need for a zipper design having positive means for securing a reclosed flexible zipper against accidental opening.
The invention is directed in part to a means for maintaining closure of a flexible zipper in a reclosable package. The invention is also directed in part to a fastener having such closure-maintaining means and to a reclosable package having such a fastener. The invention is further directed in part to a method of reclosing such a fastener. The fasteners disclosed herein comprise a flexible zipper and a device for maintaining closure of the zipper. In addition, to preventing accidental opening of the zipper, the zipper and closure-maintaining device may be designed so that the zipper closure becomes watertight when the closure-maintaining device, e.g., a string of extruded plastic, is inserted in the zipper, e.g., in a groove formed on the backside of the zipper half having a female profile.
The fastener may further comprise a slider for pressing the closure maintaining device into a groove on the zipper and/or extracting the closure maintaining device from the groove. Sliders may be designed that perform the dual functions of closing the zipper ahead of securing the closure as the slider is moved in the closing direction. Conversely, the slider can additionally or alternatively be designed to perform the dual functions of removing the closure-securing device ahead of disengaging the zipper parts when the slider is moved in the opening direction.
One aspect of the invention is a fastener comprising first and second zipper parts and a string, wherein the first zipper part comprises a first interlockable portion and the second zipper part comprises a second interlockable portion on one side of the second zipper part and a groove having an opening on an opposite side of the second zipper part. The interlockable portions are mutually interlockable. The string is seated in the groove. Optionally, the string is inserted in and/or removed from the groove by operation of a slider.
Another aspect of the invention is a fastener comprising first and second zipper parts and a string, wherein the first zipper part comprises a rib, and the second zipper part comprises a first body, a second body and a narrow strip or neck connecting the first and second bodies. The first and second bodies and the narrow strip define first and second grooves having respective openings on opposing sides of the second zipper part. The first groove is profiled to receive and hold the string, while the second groove is profiled to receive and hold the rib.
A further aspect of the invention is a package comprising: a receptacle having an interior volume and a mouth; and a fastener comprising a string and first and second interlockable zipper parts that are interlocked to close the mouth and separated to open the mouth. The first zipper part comprises a rib, and the second zipper part comprises a first body, a second body and a narrow strip connecting the first and second bodies. The first and second bodies and the narrow strip define first and second grooves having respective openings on opposing sides of the second zipper part. The first groove is profiled to receive and hold the string, while the second groove is profiled to receive and hold the rib.
Yet another aspect of the invention is a package comprising: a receptacle having an interior volume and a mouth; and a fastener comprising a string and first and second interlockable zipper parts that are interlocked to close the mouth and separated to open the mouth. The first zipper part comprises a first interlockable portion, while the second zipper part comprises a second interlockable portion on one side of the second zipper part and a groove having an opening on an opposite side of the second zipper part. The first and second interlockable portions are mutually interlockable, and the string is at least partially insertable in the groove.
A further aspect of the invention is a method of reclosing a reclosable bag having male and female zipper parts, comprising the following steps: pressing a rib of the male zipper part into a first groove formed in the female zipper part; and while the rib is inside the first groove, pressing a string into a second groove formed in the female zipper part on a side opposite to the second groove.
Another aspect of the invention is a zipper tape comprising first and second plastic zipper parts and a plastic string having a constant profile. The first zipper part comprises a rib having a constant profile and the second zipper part comprises upper and lower bodies connected by a neck and forming first and second grooves of constant profile on opposite sides of the neck. The first groove is interlockable with the rib, whereas the string is at least partially insertable inside the second groove. The neck forms a hinge allowing the upper body to pivot relative to the lower body to widen a mouth of the first groove when the string is not seated inside the second groove. This pivoting action is substantially blocked when the string is seated in the second groove.
Yet another aspect of the invention is a slider for operating a flexible zipper, comprising a housing having a passageway and a post disposed off-center in the passageway. The post has a vertical axis and a rounded profile. The housing comprises a top wall generally transverse to the vertical post, and first and second side walls connected to and projecting downward from opposing sides of the top wall. The vertical post is disposed between the first and second side walls. The top wall comprises a tapered shoulder having a surface that has a curved contour that is constant in the vertical direction and that faces toward the post and away from the second side wall.
Another aspect of the invention is a slider for operating a flexible zipper, comprising a top wall, first and second side walls connected to and projecting downward from opposing sides of the top wall, and first and second inwardly directed projections projecting from the bottoms of the first and second side walls respectively, wherein one of the side walls comprises a cutout that extends in a longitudinal direction from one end of that side wall to an intermediate portion thereof.
Other aspects of the invention are disclosed and claimed below.